I noticed that a lot of people have this issue when they try to upload an avatar or a cover image to BuddyPress profile, they cannot see the image uploaded or crop it. You can see the file being uploaded successfully but when it comes to cropping, all you can see is a dot. It is very bad for anyone running on BuddyPress, you can't have a profile without a profile picture, right?
The error looks like this:
There is no obvious way to fix it, looking all over in BuddyPress settings or turning the php.ini from inside up to see if the upload size is too small. But since the upload process went well, it shouldn't be a system error.